Research Articles

This study investigates the crucial role of sodium sulfate in pulp washing liquors and its impact on the reattachment of lignin to pulp fibres during the brownstock washing process. The dissolution of lignin during washing and its potential redeposition onto the pulp fibres is influenced by various factors. Three distinct types of pulp – unbleached, bleached, and cotton linters – were used to explore these effects. The washing experiments were conducted using industrial wash liquor and were repeated further with the addition of sodium sulfate. The resulting products of the washing process, including the liquor discharge and the washed pulp, were thoroughly evaluated. Analytical techniques, such as UV measurements of lignin content in the liquor discharge and characterization of the pulp, were employed to assess the outcomes. The findings reveal that the addition of sodium sulfate to the washing liquor results in an increase in its conductivity and ionic strength. Moreover, it was observed that lignin reattachment to pulp fibres was significantly greater when washing was performed with sodium sulfate addition. Among the pulp studied, unbleached kraft pulp exhibited the highest degree of lignin reattachment, followed by bleached kraft pulp, with cotton linters showing the least.

The influence of the temperature of the paper pulp and drying of towel papers containing polyamidoamine-epichlorohydrin (PAE – 3.5 mg/g ADM) on their wet tensile strength was investigated. The paper was produced from pulp containing 40% pine fibers and 60% eucalyptus bleached kraft fibers, heated to 25 °C, 40 °C, and 50 °C, after which the paper was dried with hot air in the temperature range of 190 to 330 °C. The aim of the research was to determine the influence of the temperature of the paper pulp and drying of the paper formed from it on the degree of PAE bonding with fibers and its self-crosslinking ability. The sheets obtained were tested for wet strength in both the machine direction (MD) and cross direction (CD). The results indicated that the paper drying temperature had a key influence on the increase in its wet strength, while heating the pulp before forming the sheets had a relatively minor effect. The increase in drying temperature to 330 °C allowed the wet tensile index (WTI) to be improved over 100% compared to drying at ambient temperature, with the highest strength demonstrated by samples formed from pulp heated to 50 °C and dried at 330 °C. Paper samples with PAE, tested wet for CD, showed strength at a level of 36 to 44% of the values obtained for MD. The obtained results contribute to the deepening of knowledge on the mechanism of increase in wet strength of PAE-modified towel papers, depending on the temperature conditions used during their production.

The utilization of natural fibers in polymer composites is increasingly popular due to their sustainability, cost-effectiveness, and favorable mechanical properties. This study introduces the novel use of Aristida hystrix fibers, processed for the first time into nano-sized particles via ball milling, to enhance dispersion and bonding within a polyester matrix. These nanoparticles were incorporated into polyester resin at various weight percentages (0 wt%, 1 wt%, 3 wt%, 5 wt%, 7 wt%, and 9 wt%), and composite laminates were fabricated using solvent casting and compression molding techniques. Mechanical properties were evaluated through tensile, flexural, and impact strength tests following ASTM standards. The composite containing 5 wt% nano fiber exhibited the optimum mechanical performance, with tensile strength of 30.13 MPa, flexural strength of 43.685 MPa, and impact strength of 1.87 kJ/m². At higher fiber loadings, particle agglomeration led to performance reduction. Water absorption studies indicated that increased nano fiber content resulted in higher moisture uptake, influencing long-term durability. Scanning Electron Microscopy (SEM) provided insights into fiber–matrix interfacial behavior, dispersion quality, and fracture mechanisms. Overall, this work establishes the first-time development of polyester composites reinforced with nano Aristida hystrix fibers, demonstrating their potential as a sustainable and high-performance material for lightweight structural applications in automotive, aerospace, and marine sectors.

With the rise of the ‘her economy’, the influence of women’s consumer demand on furniture design is becoming increasingly important. The purpose of this study was to explore the relationship between female consumers’ visual and tactile perceptions of different wardrobe furniture materials and their psychological and sensory cognition. Based on the theory of Kansei engineering, a questionnaire was designed using a semantic differential scale and a seven-point Likert scale. Female participants were invited to rate 8 sets of perceptual vocabulary for 13 representative wardrobe furniture material samples through visual and tactile perception. SPSS 27 software was used to conduct reliability and validity tests, cluster analysis, and factor analysis on the experimental data. Cluster analysis categorized the materials into three types: natural flexible materials, patterned solid wood materials, and modern materials. Factor analysis identified two key dimensions: tactile perception and visual perception. These dimensions were used to analyze the differences in sensory cognition among the three material types in female consumers. This experiment provided theoretical support for the study of female consumers’ perceptual perception of wardrobe furniture materials, and at the same time provided rational references for designers to optimise the choice of materials in wardrobe furniture design based on the emotional needs of female users.

Allergic rhinitis (AR) is an IgE-mediated inflammatory disorder of the nasal mucosa, characterized by epithelial barrier disruption, immune cell infiltration, and cytokine imbalance. This study evaluated the bioactivity of Melicope pteleifolia ethanolic extract (MP) in an ovalbumin (OVA)-induced mouse model of AR. Mice sensitized and challenged with OVA were treated orally with MP (50, 100, or 150 mg/kg, b.w.) or dexamethasone (2 mg/kg, b.w.). MP significantly and dose-dependently alleviated nasal symptoms, with the highest dose achieving effects comparable to dexamethasone. Nasal lavage fluid analysis revealed reductions in eosinophils, neutrophils, macrophages, and epithelial cells, while histological examination showed restoration of nasal-associated lymphoid tissue and septal mucosa. On the molecular level, MP suppressed NF-κB-p65 and IκBα phosphorylation, inhibited STAT3 signaling, downregulated Th17/Th2-associated markers (RORc, IL-17A, IL-5, IL-13, IL-6), and enhanced anti-inflammatory and Th1 cytokines (IL-10, IFN-γ, IL-12). Collectively, these results demonstrate the broad anti-inflammatory and immune-modulating potential of MP, highlighting its value as a promising non-steroidal candidate for AR therapy. While the present work primarily establishes pharmacological bioactivity, these insights may also provide a scientific foundation for exploring Melicope pteleifolia in future biomaterial-based biomedical applications.

The khene is a musical instrument from Thailand’s Isan region (the Thai term for Northeastern Thailand and its local Thai inhabitants). The Fast Fourier Transform (FFT) of khene signal was determined via a Pico oscilloscope. Tubes 1, 2, 3, 4, 5, 6, 7, and 8 on the right and left side produced the fundamental frequency (in hertz) as 221(A3 = 220), 255(C4 = 261), 384(G4 = 394), 443(A4 = 440), 499(B4 = 493), 591(D5 = 587), 672(E5 = 659), and 887(A5 = 880) and as 519(C5 = 523), 247(B3 = 247), 293D4(293), 329(E4 = 331), 342(F4 = 349), 395(G4 = 392), 683(F5 = 698), and 781(G5 = 783), respectively. The standard deviations of the fundamental pitch from the equal tempered scale (ETS) for tube 1, 2, 3, 4, 5, 6, 7, and 8 on the right and left side were ± 1, ± 6, ± 10, ± 3, ± 6, ± 4, ± 13, ± 7 and ± 4, ± 0, ± 0, ± 2, ± 7, ± 3, ± 15, ± 2 Hz, respectively. The tunings were remarkably similar with the diatonic scale of ETS. The linear equation for the partial frequency versus harmonic number for tube 1 to 8 from the right and the left side is given by y1 = 220x + 1.31, y2 = 255x + 0.34, y3 = 384x + 0.77, y4 = 443x + 0.19, y5 = 499x – 0.13, y6 = 591x + 1.82, y7 = 672.x + 2.35, and y8 = 887x, and y1 = 519x + 0.14, y2 = 247x – 0.07, y3 = 293x + 0.40, y4 = 331x – 5.49, y5 = 341x + 1.70, y6 = 395x + 0.38, y7 = 683x – 0.4, and y8 = 782x – 0.50, respectively. The harmonic number of tubes 1 to 8 on the right and left side were 16, 14, 9, 8, 7, 6, 5, 7, and 7, 14, 10, 10, 11, 9, 5, 4, respectively.

Hydrodistillation (HD), organic solvent extraction (OSE), and supercritical fluid extraction (SFE) were compared in terms of the chemical composition and antifungal activity of leaf essential oils from Chamaecyparis formosensis and C. obtusa var. formosana. Gas chromatography–mass spectrometry revealed notable differences among extraction methods. In C. formosensis, HD-derived oil was dominated by α-pinene (83.4%), SFE-derived oil by kaur-16-ene (51.1%), and OSE-derived oil by phytol (44.4%). In C. obtusa var. formosana, HD oil was rich in sabinene (36.2%) and thujopsene (22.5%), SFE oil in totarol (50.9%), and OSE oil in thujopsene (27.6%) and cedrol (24.8%). Bioassays demonstrated that OSE oil of C. formosensis exhibited the strongest inhibitory effects against Trichoderma sp., Trametes versicolor, Laetiporus sulphureus, and Gloeophyllum trabeum. For C. obtusa var. formosana, HD oil was most effective against Trichoderma sp. and L. sulphureus, whereas SFE oil was most active against G. trabeum. These results highlight the strong influence of the extraction method on both chemical composition and antifungal efficacy of leaf essential oils.

Manganese peroxidase (MnP) is a lignin-degrading enzyme required in the ligninolytic process catalyzing oxidation of Mn²⁺ to Mn³⁺. It has the ability to degrade nitroaromatic compounds, chlorophenols, and polycyclic aromatic hydrocarbons, all of which contribute to organic pollution. In this work, an indigenous strain of white-rot fungus Pleurotus ostreatus (oyster mushroom) was employed for hyperproduction of MnP using response surface methodology (RSM) under solid state fermentation through screening of local biomass. Among the parameters, 14 days incubation period, pH 4, 30 °C temperature, 8.0 g substrate concentration, 4.5 mL inoculum size, 60% moisture content, 2.87 g nitrogen supplement, and 0.082 g magnesium sulphate were found as the optimized conditions for production of manganese peroxide. Peanut shell was found as the best substrate for maximum production of enzyme (74.70 U/mL). The degradation of guaiacol as a substrate by MnP was also confirmed through Fourier Transform Infrared spectroscopy, which showed the absence of a peak of -C=O at 1636.6 cm^-1 and –OH at 3331.4 cm^-1 as structural components of guaiacol, after degradation by MnP. Peanut shell is easily available as agriculture residue. Therefore, hyper-produced MnP from P. ostreatus could lead to cost effective exploitation of further enzymes for industrial applications.

The nail-holding performance of two major commercial wood species in southern China, P. massoniana (Masson pine) and C. lanceolata (Chinese fir), were investigated in this paper. Nail-holding strength tests on the two kinds of wood were conducted using self-tapping screws and round steel nails, respectively, with the focus on analyzing the impact law of guiding bore diameter on nail-holding performance. Without the guiding hole, the nail-holding force of both kinds of nails was poor. When the guiding hole diameter increased moderately, the nail-holding force showed an upward trend. Nevertheless, if the guiding hole diameter was too large, the nail-holding force would drop sharply. The nail-holding force of self-tapping screws peaked when the guiding hole diameter was 2.0 mm, and that of round steel nails reached the maximum when the guiding hole diameter was 2.5 mm. In addition, there were remarkable differences in the nail-holding force performance of P. massoniana and C. lanceolata wood under different guiding hole diameters, and their load-displacement curve characteristics also varied. Reasonable design of the diameter of the guiding hole can significantly enhance the nail-holding performance of wood, ensuring the stability and reliability of wood structure connections.

The agricultural sector generates considerable amounts of waste annually, particularly during harvest periods. This study explored the potential of pineapple (Ananas comosus Merr.) leaves, a cellulose-rich byproduct of the pineapple industry, as a sustainable raw material for paper production. Mechanical strength, renewability, and cost-effectiveness make pineapple leaves a promising alternative for eco-friendly papermaking. The research focused on analyzing the chemical composition of the leaves, optimizing the pulping process, and evaluating the physical properties of the resulting paper. Utilizing TAPPI test methods, the chemical analysis revealed high concentrations of holo-cellulose (82.6%), alpha-cellulose (69.7%), and hemicellulose (12.9%), along with relatively low levels of solvent extractives (14.7%) and ash content (4.9%). The physical attributes of the produced paper include a tensile index of 50.1 Nm/g, a tear index of 6.33 mNm²/g, and a burst index of 3.31 kPa·m²/g. Additionally, the brightness of the unbleached paper was measured at 28.8 % ISO, which was increased to 69.7 % ISO after the bleaching process. Pineapple leaves possess more alpha cellulose than most other wood and non wood sources and paper made from these leaves has shown better physical properties.  These findings underscore the potential of pineapple leaves as a viable alternative pulp source for the paper industry, contributing to the advancement of sustainable and environmentally friendly manufacturing practices.